Thio bis succinimides



United States Patent 3,357,990- THIO BIS SUCCINIMIDES Billy D. Vineyard, Bellefo'ntaiiie Neighbors, Mo., asslgnor to Monsanto o'nipany.,-St; Louis, M'oi, a corporation of Delaware i v 7 Renewing. Original applicatioi1- l \lev .,6, 1961, Ser. No,

1 50302, n'ow Patent N6.- 3,299',12l, dated Jan. 17,

1967; Divided-and this"applicatidn-'Aug; 16, 1966, Ser.

Not-592,247-

xBsr Rircror nrscnosuna Tina his succini rnid es which are useful as lube oil additives.

The present application is a division of copending application Ser No. 150,202, filed Nov. 6, 1961, now Patent No. 3,229,121.

This invention relatesto novel thioesters, their nitrogen derivatives and methods of preparing the same; More particularly, the invention relates to novel thio bis succinimides.

Specifically, the invention is directed to thio bis half esters of succinic acids and nitrogenization products thereof including thio bis succimirnides. The amine derivatives of these half esters are lube oil additives, serving a-dual role as deterge'nt disper'sants and as antioxidants. It is therefore an object of this invention to provide new and' novel thio bis (acid esters) and their amine derivatives; A more specific object of this invention is to provide novel thio bis suc'cinimides'.

In accordance with this invention these and other ob jects are accomplished,- generally speaking, by reacting hydrogensulfide in' the presence of a basic catalyst with an acid or half-esterof maleic,citraconic or itaconicacid toobtain the corresponding thio bis (acid succinate) or his ('acid methyl su'ccinate). Thethioesters thusprepared can beemployed as antioxidant oil additives, or can be readily nitrogenized in-the synthesis of their amine derivatives';

More specifically this invention contemplates the pie paration of the thioesters under consideration by a process wherein hydrogen sulfide, a basic' catalyst, andan acid" or half ester of maleic, citraconic or itaconic acid are placed in intimate contact and the'contaet maintained until the reaction between them is substantially complete and the reactants converted to the corresponding thio bis (acid succinate). The requisite intimate contact is preferably obtained by preparing a solution of the reactants and the catalysts, or by passing hydrogen sulfide througha solution of the acid" ester and' the basic catalyst. However, when hydrogen sulfide and the acid ester are mutually soluble, the inert solvent and' recovery problem's attendant thereto can be completely eliminatedi I p The reaction between hydrogen sulfide and the acid maleate can be normally carried out at room temperature, that is about 20 C., butit may bep'refered' to accelerate the reaction by utilizingia' somewhat higher temperature'. Generally speaking; the" temperatures employed are in the range between room temperature and the boiling point of the reaction mixture. After the reaction has gone to completion, the residual thiobis (acid-'succinate) produced can be best're cover ed by removal of the solvent medium by conventional riiea'us; such as vacuum distil lation.

A variety of organic solvents or solvent mixtures, either polar or non-polar, can be used in accordance with this invention. It is only necessary that they be capable of dissolving the reactants and the catalysts while not reacting with them. Suitable non-polar solvents include ben- 3,357,999 Patented Dec. 12, 1967 zene, toluene, xylene; chloroform; carbon tetrachloride and the like.- Satisfactory polar solvents include water, dioxane, tetrahydr-ofuran, acetone, ethyl methyl ketone, diethyl-ether, glycol dimethyl-ether, mixtures of dioxane and dimethylformamide'and the like.- The amount of solvent is not particularly critical but must be sufficient to insure substantial solution of the reactants and" the catalysts. For economic reasons however, it is preferred to maintain the amount of solvent to a minimum so' as to eliminate excessive costs in its subsequent removal.

Preferably, when the reaction is executed under pressure, one mole of hydrogen sulfide is introduced into' the reaction mixture for each two moles of the half ester present. The ratio" can, of course, be varied somewhat, but for optimum'yields and economy of operation, it is preferred to approximate these proportions. However, for a non-pressure reaction, an excess of hydrogen sulfide is passed through a solution ofthe half ester until the reaction'is complete. This excess compensates for any hydrogen sulfide that passesthrough the reaction mixture without reacting with the acid maleate.

The basic catalyst used in the preparation of the thio bis (acid esters) can be any of'a wide variety of basic components. For example, one may use a tertiary amine, such as triethylamine, b'enzyldimethylamine, triethyle'nediarnine', pyridine and the like. However, alkali alkoxides and alkaline earth alkoxides, such as sodium methylate, potassium ethyla'te, alkali thiola'tes and alkaline earth thiolates, such as sodium' methylthiolate, lithium ethylthiolate, alkali and alkaline earth metal salts of phenols and thioph'enols, including sodium phenate, sodium thiophenate and anhydrous quarternary ammonium hydroxides, such astrime'thyl benzyl ammonium hydroxide and the lilie can be used with equal facility. Other bases such as sodium amide, lithium amide, sodium hydride, lithium hydride, sodium sulfide and the like also may be used. It has been'fourid that the reactions of this invention can be executed using as little as about 0.01% catalyst based on the weight of hydrogen sulfide. In most instances, it is preferred to use between about 0.1% and about 3% catalyst to insure efiicient catalysis. Larger amounts can, of course, be used, but they serve no useful purpose.

The exact manner in which these catalysts function is not precisely known. It is believed, however, that the mechanism of this reaction may be represented as a Michael t'yp'e of addition of a thi'ol anion to a polarized double bo'ndrThe apparent function of the base is to effect ionization of hydrogen sulfide to its anion.

The following reaction is illustrative of the preparation of'thio bis (acidsuccin'ates) by the reaction of hydrogen sulfide'with" an acid ester of m'aleic acid:

CHCO0P CH-COOR) CH-COOP (1112-00013 In the above equation R' represents a hydrocarbon radical containing between 1 and 20 carbon atoms. This radical may bealkyl, alkenyLaryl or alkylaryl, and substituted or unsubstituted. The particular nature of radical R and the presence or absence of substituents'thereon has little if anyeffect no the operability of theprocess. Thus, when it is desired to impartparticular characteristics to, or to enhance the properties of the resultant thio bis (acid succinate R can contain one or more substituents, such as halogens, nitro'groups; and the like.

addition :to their utility per se, the thio bis (acid succinate's) of the present invention are uniquely useful in the preparation of their novel amine derivatives. In fact, they represent the only group of compounds that can be economically used in the commercial production of such amine oil additives. These amine derivatives are readily prepared by nitrogenization of the thio bis (acid succinates). This is accomplished in the case of the acid quired for the preparation of succinamides.

CHz-COOR I ZR'NH: S- CH-COOH 2 S CH-CO OHz-CO 2 In this reaction R and R are hydrocarbon radicals Containing between 1 and 20 carbon atoms, and preferably a total at least 12 carbon atoms to insure oil solubility. Here again, the radicals may be alkyl, alkenyl, aryl or alkylaryl, and substituted or unsubstituted. When substituents are present, they may be those enumerated above in connection with the reaction for the formation of the thio bis (acid succinates).

The reaction, in a solvent of the type enumerated above, between a primary amine and a thio bis (acid succinate) in a molar ratio of about 2:1 results in the formation of the corresponding succinimide. In order to obtain satisfactory yields of the succinimides, the reaction temperature must be maintained between about 120 C. and about 150 C., and the alcohol and water formed removed throughout the course of the reaction. At temperatures below 120 C. the yield of the succinimide drops off appreciably, and a mixed product containing considerable proportions of the ester-amides and ester-amine salts is formed. On the other hand, temperatures above about 150 C. are diflicult to maintain and have objectionable side reactions.

The thio bis succinyl compounds of the present invention range in physical properties from clear fluid to oily liquids. Their physical form is apparently dependent at least partially on the size and structure of the groups contained therein. Most of these compounds are insoluble in water, but readily soluble in commercially available organic solvents. Also those having higher molecular weights are soluble or dispersible in all proportions with hydrocarbon lubricating oils. The invention and the manner in which its objects are achieved will be more readily understood by reference to the following preferred enibodiments thereof. In these examples and throughout the specification, all proportions are expressed in parts by weight unless otherwise designated.

EXAMPLE I 2,2-fhi bis(ethyl acid succinate) Between about 0.1 and about 0.2 mole of hydrogen sulfide and about 0.5 gram triethylamine were dissolved in about 150 cc. of dioxane at a temperature of about 25 C. Then approximately 28.8 grams (0.2 mole) of ethyl acid maleate were added in small increments over an hour and a half period. During this time hydrogen sulfide was also added at a sufiicient rate to maintain the solution saturated with respect to this gas. The reaction mixture was then heated to about 40 C. for 8 hours while maintaining the hydrogen sulfide saturation. At the end of this period, the reaction was substantially complete and the solvent removed by vacuum distillation so as to separate it from the residual 2,2-thio bis(ethyl acid succinate). The identity of this material was confirmed by chemical and infrared analyses.

EXAMPLE II Thio bis(oleyl succinimide) About 20.3 grams (0.06 mole) of oleyl amine were added to a solution of about 10 grams (0.03 mole) of thio bis(ethyl acid succinate) in approximately cc. of toluene at about 30 C. The resultant reaction mixture was then heated to and maintain within the approximate temperature range of 140 C. for about 6 hours. During this period the water and ethanol formed as reaction by-products were continuously removed by means of a suitable trap. At the end of the 6 hour heating interval, the reaction was substantially complete. Subsequently the toluene was removed by distillation and the residual thio bis(oleyl succinimide) was characterized by infrared, nitrogen analysis and acid number.

In like manner many other thio bis succinyl compounds can be prepared in accordance with the present invention: The following compounds are illustrative of such products:

thio bis(ethyl succinimide) thio bis(dodecyl succinimide) thio bis( 3-oleylaminopropyl succinimide) thio bis(stearyl succinimide) thio bis oleyl succinimide) thio bis(3-dimethylaminopropyl succinimide) The terms succinyl, succiniate and the like are used in their broadest sense throughout the specification and in the appended claims. These terms include methyl succinyl and methyl succinate, as well as the unsubstituted succinyl compounds. Thus derivatives of maleic, citraconic and itaconic acids are encompassed by them.

Numerous modifications will readily suggest themselves to those skilled in the art. Thus while the invention has been described with particular reference to specific embodiments, it is to be distinctly understood that it is not limited thereto but is to be construed broadly and restricted solely by the scope of the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A thio bis succinimide having the formula I s- CH O' GE -(H3 2 wherein R is hydrocarbon selected from the group consisting of alkyl, alkenyl, aryl or alkylaryl and is of a maximum of 20 carbon atoms.

2. Thio bis(ethyl succinimide).

3. Thio bis(dodecyl succinimide).

4. Thio bis(3-oleylaminopropyl succinimide),

5. Thio bis(stearyl succinimide).

6. Thio bis(oleyl succinimide).

7. Thio bis(3-dimethylamin0propyl sucpinirnide),

No references cited.

ALEX MAZEL, Primary Examiner. .l. TOVAR, Assistant Examiner. 

1. A THIO BIS SUCCINIMIDE HAVING THE FORMULA
 4. THIO BIS(3-OLEYLAMINOPROPYL SUCCINIMIDE).
 7. THIO BIS(3-DIMETHYLAMINOPROPYL SUCCINIMIDE). 